1. Field of the Invention
This invention relates to lubricating oil compositions. More particularly it relates to lubricating oil compositions that are excellent in antiwear properties, anti-seizure properties, and corrosion resistance, and are suitable for gear oils, and bearing oils, also for internal combustion engine oils and automatic transmission fluids, and further for hydraulic fluids, metal working fluids, and the like.
2. Description of the Related Art
Lubricating oils for various applications are generally required to have anti-seizure properties and antiwear properties for many situations. Especially, lubricating oils that require a high degree of anti-seizure property and antiwear property need incorporation of extreme pressure agents, which has resulted in increased corrosion of metals and posed a great problem in practice.
Metal deactivators have been added to lubricating oils incorporated with extreme pressure agents to solve this problems, but has given rise to a question of decreasing anti-seizure property and antiwear property as side effects.
Recently there was a proposal for preparation of lubricating oil compositions with improved anti-seizure property and antiwear property by incorporating to the base oil organomolybdenum compounds in combination with mono-, di-substituted phosphates or mono-, di-substituted phosphites (Japanese Patent Application Laid-Open No. 75995/1984).
The lubricating oil compositions described above have shown some extent of improvement in anti-seizure property and antiwear property but have still left the problem of failure in reducing metal corrosion unsolved.